If $8a + 3b = 7$ and $5x + 5y = 8$, what is $35y + 35x + 40a + 15b$ ?
Answer: $= 40a + 15b + 35x + 35y$ $= (5) \cdot (8a + 3b) + (7) \cdot (5x + 5y)$ $= (5) \cdot (7) + (7) \cdot (8)$ $= 35 + 56$ $= 91$